The Latest Energy Storage Gizmo Is An “Ocean Battery” With A Bladder

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The Intertubes are absolutely on fire with news about a new “ocean battery” energy storage invention that uses gigantic undersea bladders to soak up excess energy from offshore wind turbines. The idea is not as crazy as it sounds — at least the judges at the 2022 Consumer Electronics Show in Las Vegas don’t think so.

The Seawater Version Of Compressed Air Energy Storage

If you’re thinking this is bladder idea is similar to compressed air storage, well, kind of. The foundational element is the fact that wind energy runs on its own timetable, and its schedule is often out of sync with demand for electricity. Energy storage systems enable wind turbines to keep working even when demand is low.

In compressed air storage, the formula is pretty straightforward: use excess electricity to run air compression systems when demand is low, then release the air to run turbines that generate electricity when demand is high.

The “ocean battery” undersea energy storage concept is more similar to pumped hydro storage, in which renewable energy is used to pump water uphill to a reservoir. When extra electricity is needed, gravity is deployed to release the water downhill to hydropower generators.

A Better Battery For Offshore Wind Farms

The Dutch startup Ocean Grazer wowed the judges at CES 2022 with its contribution to the undersea storage field, garnering a CES 2022 “Best of Innovation” award for its Ocean Battery technology.

Relatively speaking, it’s been a short road trip from lab to market for the company. Ocean Grazer spun off from the University of Groningen in 2014 as a study project, then made a quick pivot into commercial development in 2019.

Ocean Grazer apparently won its “Best of” title not only on account of the technology itself, but on its potential for application at offshore wind farms.

“The Ocean Battery is a Breakthrough solution based on our proprietary Key Enabling Technology to solve the huge Challenge of Balancing Supply & Demand for the Global offshore e-Power industry due to Intermittent Production of Wind Power,” Ocean Grazer explains.  “Our Patented and Sustainably produced Ocean Battery system, substantially Lowers the CapEx for the massively expensive Offshore Power Grid, generating a very high ROI for the unique Ocean Battery.”

Ocean Grazer notes that the rush to develop offshore wind farms will result in wild fluctuations in supply and demand, unless energy storage scales up. Energy storage will help avoid — if not eliminate — brownouts and blackouts when the wind dies down. It will also enable producers to reserve excess kilowatts during periods of oversupply, avoiding the impact of low or even negative pricing on their bottom lines.

Undersea Energy Storage Vs. Pumped Hydro: Compare And Contrast

A number of firms have been tackling the challenge of undersea energy storage, and the challenges are many. In addition to difficulties in deploying, maintaining and repairing undersea systems, saltwater corrosion is an issue.

Despite the challenges, Ocean Grazer points out that its system has a key advantage over pumped hydro storage: with its “in-a-box” undersea system, you don’t have to find a spot to build a new pumped hydro reservoir on land.

That’s a significant advantage. Here in the US, pumped hydro has been the number one bulk, long duration storage technology for many years, and it will probably continue to maintain that status. However, it will be difficult if not impossible to build any significant number of new pumped hydro reservoirs.

Of course, you can’t just plop down huge undersea structures just anywhere without running into environmental impacts and competing commercial uses. Nevertheless, Ocean Grazer has come up with a formula that could work, by linking its system with approved wind farms that have already undergone extensive review.

“Our solution is embedded into the seabed and can be installed in between or next to existing and new wind farms to enhance the stability, reliability, and profitability of your project,” Ocean Grazer explains, further noting that floating solar and tidal power systems are also candidates for development.

How Does It Work?

The meat of the system is a high pressure, flexible bladder contained within a concrete reservoir, buried under the seabed. To charge the battery, you pump seawater from the rigid reservoir into the bladder.

Pressure within the bladder does the rest. When extra kilowatts are needed, water is released to run turbines for generating electricity.

The pumps and turbines are based on existing technology and are housed in an accessible machine room.

Speaking of comparisons with pumped hydro storage on land, the US Department of Energy has been trying to get the pumped hydro industry to bring down costs by standardizing and modularizing their technology. Ocean Grazer has a jump on that angle:

The Ocean Battery is constructed based on standardized building blocks and makes it possible to mix and merge storage volume and capacity. The storage volume can be sized by connecting the exact amount of rigid reservoir elements, each with a storage volume of 10 MWh , to create the desired storage volume,” they explain.

Undersea Energy Storage Vs. Battery Energy Storage

Zooming out to the big picture, nothing will stop the lithium-ion battery juggernaut any time soon. However, the Li-ion field abounds with environmental pitfalls, especially concerning the use of critical metals. These issues are being ameliorated through recycling, sustainable sourcing and other efficiencies, but the global electrification movement could overwhelm this progress  unless alternative energy storage technologies are available.

In that regard, Ocean Grazer points out that its system kills two sustainability birds with one stone. One involves the use of critical materials, of which there are none.

The other involves the restorative potential of Ocean Grazer’s system:

The construction of Ocean Battery systems in wind farms provides a perfect opportunity to create artificial safe havens for marine life to rebuild their ecosystems. Fishery and shipping and other activities by mankind in coastal areas, especially bottom trawl netting, have destroyed marine communities at the seabed. In many coastal areas around the globe people are building artificial reefs, flexible geotextile structures etc. to achieve this. With the installation of the Ocean Battery at the seabed these structures come for free and allow marine life to recover and flourish.”

They might just be on to something. A few years ago, New York City famously repurposed many toilets to serve as oyster restoration beds among its local waterways. Now the idea is gaining new legs as a flood control strategy, so stay tuned for more on that.

Follow me on Twitter @TinaMCasey.

Image: Undersea storage system with wind and solar power courtesy of Ocean Grazer.

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Tina Casey

Tina specializes in advanced energy technology, military sustainability, emerging materials, biofuels, ESG and related policy and political matters. Views expressed are her own. Follow her on LinkedIn, Threads, or Bluesky.

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